Iis – Backup of All websites with MSDeploy

With IIS7, it gets MUCH easier. What you're looking for is "Shared configuration". You can set that at the global level on the server. With that, you can have hot-hot, or hot-warm like you described.

On the primary server, use "export" under shared configuration. That will save the server's Machine Key (different than ASP.NET's machineKey). That ensures that all encrypted data can be ready on the new server. It will also save applicationHost.config and administration.config. Once you do an import on the 2nd server, applicationHost.config and administration.config can (and should) be 100% the same between both servers.

So, you can use DFS-R to keep the configs 100% in sync automatically, or use something like robocopy to do it at regular intervals, depending on your favorite tool.

You don't need to point to a different path on your primary server either. Just use the export for the sake of the 2nd server.

The Web Deployment Tool is great, but for what you're talking about, Shared Configuration is a better fit.

It should be noted that certificates aren't stored in those files so you need to do them manually when you set them up, or use something else (like Web Deployment Tool) for keeping those in sync.

Another thing you can consider for an inexpensive but powerful load balancer is Microsoft's new ARR technology. (Application Request Routing)

I'd consider having a look at the Backup Exec System Recovery Server Edition (Windows) and Backup Exec System Recovery Linux Edition products. The Symantec Backup Exec System Recovery Virtual Edition product might fit your ESXi host better, as well, so have a look at it. I believe they hit all your requirement points. (I'm not making a personal recommendation, but these look like they might fit your bill. I've worked around the windows product and, frankly, don't like it. That's probably my personality and preferences talking more than anything, though.)